javascript - Pass data from chrome extension to webpage -

i able pass data webpage chrome extension. code goes follows.

var id = "myextensionid";     chrome.runtime.sendmessage(id, { messagefromweb: "sample message" }, function (response) { }); 

i able tab id @ extension side. how can send data extension tab? following code correct?

chrome.runtime.onmessageexternal.addlistener(     function(request, sender, sendresponse) {         if (request.messagefromweb) {             console.log(request.messagefromweb);         }          chrome.tabs.sendmessage(sender.tab.id,{ greeting: "hello" });     } ); 

the code, chrome.tabs.sendmessage(sender.tab.id,{ greeting: "hello" }); not throw error. how should listening @ web page events extension?

from content script website script

because content script , scripts in website can see same dom, can use communicate between them. easy as:

content script:

// data want sent var data = {     random: 'some data',     more: 'more data' };  // send data through dom event document.dispatchevent(new customevent('csevent', {detail: data})); 

website script:

// listen crx event document.addeventlistener('csevent', function (event) {     var data = event.detail;      // data crx }); 

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from content script background script

how depends on type of connection need: one-time or long-lived. chrome developer page messaging:

there simple api one-time requests , more complex api allows have long-lived connections exchanging multiple messages shared context.

if want send response back, here example:

chrome.runtime.onmessage.addlistener(     function(request, sender, sendresponse) {         console.log(sender.tab ?                 "from content script:" + sender.tab.url :                 "from extension");          sendresponse({farewell: "message back!"});     }); 

edited add content script website script way